doc: dependencies and user privileges (#91)

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#### Relevant issue or PR
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them here. Only link something if it is directly relevant. -->

Closes #88.

#### Description of changes
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*why*. -->

- Added description of dependencies for users who installed Docker's
CLI, rather than via Docker Desktop (which is only available for Windows
and macOS, with limited support for some Linux distros).
- Described steps to add user to the `docker` group, to avoid Tesseract
OCR gotcha when using `sudo tesseract`

#### Testing done
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manually in stagingrepo#123", screenshots of a terminal session that
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In progress.

#### License

- [X] By submitting this pull request, I confirm that my contribution is
made under the terms of the [Apache 2.0
license](https://pasteurlabs.github.io/tesseract/LICENSE).
- [X] I sign the Developer Certificate of Origin below by adding my name
and email address to the `Signed-off-by` line.

<details>
<summary><b>Developer Certificate of Origin</b></summary>

```text
Developer Certificate of Origin
Version 1.1

Copyright (C) 2004, 2006 The Linux Foundation and its contributors.

Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.


Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified
    it.

(d) I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.
```

</details>

Signed-off-by: Jacan Chaplais jacan.chaplais@simulation.science

---------

Co-authored-by: Dion Häfner <dion.haefner@simulation.science>

Author: jacanchaplais

docs/content/introduction/installation.md

@@ -3,7 +3,7 @@
 ## Basic installation
 
 ```{note}
-Before proceeding, make sure you have a [working installation of Docker](https://docs.docker.com/engine/install/) and a modern Python installation (Python 3.10+), ideally in a [virtual environment](https://packaging.python.org/en/latest/guides/installing-using-pip-and-virtual-environments/).
+Before proceeding, make sure you have a working installation of Docker ([Docker Desktop](https://www.docker.com/products/docker-desktop/) or [Docker Engine](#installation-docker)) and a modern Python installation (Python 3.10+), ideally in a [virtual environment](https://packaging.python.org/en/latest/guides/installing-using-pip-and-virtual-environments/).
 ```
 
 The simplest way to install Tesseract Core is via `pip`:
@@ -18,6 +18,29 @@ Then, verify everything is working as intended:
 $ tesseract list
 ```
 
+(installation-docker)=
+## Installing Docker
+
+[Docker Desktop](https://www.docker.com/products/docker-desktop/) ships with everything you need to run Tesseract Core, including the Docker Engine CLI, Docker Compose, and Docker Buildx. It also includes a GUI for managing containers and images.
+It is available for Windows, macOS, and Linux for Debian and Fedora based distros.
+
+If your system is not supported by Docker Desktop, or you prefer a more minimal setup, you will need to install the [`docker` engine CLI](https://docs.docker.com/engine/install/) together with some required plugins:
+
+1. [`docker-buildx`](https://github.com/docker/buildx)
+2. [`docker-compose`](https://github.com/docker/compose)
+
+To use Tesseract without `sudo`, you will need to add your user to the `docker` group. See [Linux post-installation steps for Docker Engine > Manage Docker as a non-root user](https://docs.docker.com/engine/install/linux-postinstall/#manage-docker-as-a-non-root-user), or run:
+
+```bash
+$ sudo usermod -aG docker $USER
+```
+
+Then, log out and back in to apply the changes.
+
+```{warning}
+Using `sudo tesseract` may bypass active virtual environments and shadow the `tesseract` command with [conflicting executables](#exe-conflicts). To avoid this, make sure you're using the correct `tesseract` executable, or add your user to the `docker` group (and omit `sudo`).
+```
+
 (installation-runtime)=
 ## Runtime installation
 
@@ -38,6 +61,7 @@ Some shells use `[` and `]` as special characters, and might error out on the `p
 
 Tesseract is fully supported on Windows via the Windows Subsystem for Linux (WSL). For guidance, please refer to the [official documentation](https://docs.microsoft.com/en-us/windows/wsl/).
 
+(exe-conflicts)=
 ### Conflicting executables
 
 This is not the only software called "Tesseract". Sometimes, this leads to multiple executables with the same name, for example if you also have [Tesseract OCR](https://github.com/tesseract-ocr/tesseract) installed. In that case, you may encounter the following error:
@@ -62,6 +86,24 @@ You can always confirm what executable the command `tesseract` corresponds with
 $ which tesseract
 ```
 
+### Missing user privileges
+
+If you lack permissions to access the Docker daemon, running e.g. `tesseract build` will result in the following exception:
+
+```bash
+$ tesseract build examples/helloworld
+RuntimeError: Could not reach Docker daemon, check if it is running. See logs for details.
+```
+
+You can resolve this by adding your user to the `docker` group.
+See [Linux post-installation steps for Docker Engine > Manage Docker as a non-root user](https://docs.docker.com/engine/install/linux-postinstall/#manage-docker-as-a-non-root-user), or run:
+
+```bash
+$ sudo usermod -aG docker $USER
+```
+
+Then, log out and back in to apply the changes.
+
 (installation-dev)=
 ## Development installation